Hi, On 24/08/2020 15:32:22+0200, Bastian Krause wrote: > On 8/24/20 1:31 PM, Bastian Krause wrote: > > > > On 4/15/20 8:56 PM, Alexandre Belloni wrote: > >> On 15/04/2020 18:37:00+0200, Bastian Krause wrote: > >>> Signed-off-by: Bastian Krause <bst@xxxxxxxxxxxxxx> > >>> --- > >>> Documentation/devicetree/bindings/rtc/rtc-ds1307.txt | 3 +++ > >>> 1 file changed, 3 insertions(+) > >>> > >>> diff --git a/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt b/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt > >>> index 66f0a31ae9ce..987a0c9e0cd7 100644 > >>> --- a/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt > >>> +++ b/Documentation/devicetree/bindings/rtc/rtc-ds1307.txt > >>> @@ -34,6 +34,9 @@ Optional properties: > >>> - trickle-diode-disable : ds1339, ds1340 and ds 1388 only > >>> Do not use internal trickle charger diode > >>> Should be given if internal trickle charger diode should be disabled > >>> +- aux-voltage-chargeable: rx8130 only > >>> + Epsons's rx8130 supports a backup battery/supercap. > >>> + This flag tells whether the battery/supercap is chargeable or not. > >>> > >> > >> I think we should make that a generic property and this should supersede > >> trickle-diode-disable which is a bit wonky as I would prefer the default > >> to be disabled instead of enabled with the current semantics. > > > > Alright, I think I know how to transform the RTC drivers. > > > > One question about the DTs though: > > > > This means we should remove "trickle-diode-disable" from all upstream > > DTs and add "aux-voltage-chargeable" to all upstream DTs that use a RTC > > compatible whose driver care in their probe function for > > "trickle-diode-disable", right? > > Sorry, forget that. > > Here's the situation: > > Currently there is a switch to explicitly disable charging, so the > default is to charge. We cannot introduce another boolean switch to turn > that the other way around, because that would change the default and > break backwards compatibility. > > The only way I can think of is to introduce "aux-voltage-chargeable" not > as a boolean switch but as an integer, without any default. If this > property is not available, the drivers should simply do what they did > prior to this change (look for the legacy trickle-diode-disable, use the > default they used before). > > Are you okay with that? > I agree boolean should be avoided in RTC drivers because we need a way to express "don't change this value". > Some more context: > > I originally tried to add a chargeable flag for rx8130. Prior to this > patch, there was no need to set "trickle-diode-disable" for this, > because the driver did not pass the chargeable flag to the RTC. With the > patch the default would have been to charge as long as > "trickle-diode-disable" is not there. So there's a change in behavior. > Yes, IIRC, my point was simply to move the documentation for aux-voltage-chargeable to the generice rtc binding documentation, Documentation/devicetree/bindings/rtc/rtc.yaml For now, you sould keep support for trickle-diode-disable but it has to be superseded by aux-voltage-chargeable if present. Is that more clear? -- Alexandre Belloni, Bootlin Embedded Linux and Kernel engineering https://bootlin.com
